Buffer::{iterator_at,clamp} takes an optional avoid_eol parameter

when avoid_eol is true, clamping does avoid end-of-line if possible

src/buffer.cc

@@ -55,9 +55,10 @@ Buffer::~Buffer()
     assert(m_change_listeners.empty());
 }
 
-BufferIterator Buffer::iterator_at(const BufferCoord& line_and_column) const
+BufferIterator Buffer::iterator_at(const BufferCoord& line_and_column,
+                                   bool avoid_eol) const
 {
-    return BufferIterator(*this, clamp(line_and_column));
+    return BufferIterator(*this, clamp(line_and_column, avoid_eol));
 }
 
 BufferCoord Buffer::line_and_column_at(const BufferIterator& iterator) const
@@ -78,14 +79,15 @@ BufferSize Buffer::line_length(BufferPos line) const
     return end - m_lines[line].start;
 }
 
-BufferCoord Buffer::clamp(const BufferCoord& line_and_column) const
+BufferCoord Buffer::clamp(const BufferCoord& line_and_column,
+                          bool avoid_eol) const
 {
     if (m_lines.empty())
         return BufferCoord();
 
     BufferCoord result(line_and_column.line, line_and_column.column);
     result.line = Kakoune::clamp<int>(0, m_lines.size() - 1, result.line);
-    int max_col = std::max(0, line_length(result.line) - 2);
+    int max_col = std::max(0, line_length(result.line) - (avoid_eol ? 2 : 1));
     result.column = Kakoune::clamp<int>(0, max_col, result.column);
     return result;
 }

src/buffer.hh

@@ -130,11 +130,16 @@ public:
     BufferSize     character_count() const;
     BufferSize     line_count() const;
 
-    BufferIterator iterator_at(const BufferCoord& line_and_column) const;
+    // returns an iterator at given coordinates. line_and_column is
+    // clamped according to avoid_eol.
+    BufferIterator iterator_at(const BufferCoord& line_and_column,
+                               bool avoid_eol = false) const;
     BufferCoord    line_and_column_at(const BufferIterator& iterator) const;
 
     // returns nearest valid coordinates from given ones
-    BufferCoord    clamp(const BufferCoord& line_and_column) const;
+    // if avoid_eol, clamp to character before eol if line is not empty
+    BufferCoord    clamp(const BufferCoord& line_and_column,
+                         bool avoid_eol = false) const;
 
     const String& name() const { return m_name; }
 

src/editor.cc

@@ -113,7 +113,7 @@ void Editor::move_selections(const BufferCoord& offset, bool append)
     for (auto& sel : m_selections.back())
     {
         BufferCoord pos = m_buffer.line_and_column_at(sel.last());
-        BufferIterator last = m_buffer.iterator_at(pos + BufferCoord(offset));
+        BufferIterator last = m_buffer.iterator_at(pos + offset, true);
         sel = Selection(append ? sel.first() : last, last);
     }
 }